1. Field of the Invention
This invention relates generally to liquid ring compressors, and in particular to an improved liquid ring compressor construction including a calibrated gas input opening for reducing the pressure increase of the gas pumped by the impeller of the compressor ahead of the output openings of the control disc of the compressor in the direction of rotation of the impeller.
2. Description of the Prior Art
Liquid ring compressors including a separate gas input opening in the control disc of the compressor near the delivery space of the impeller between the suction and output openings of the control disc are known in the art. See, for example, German Patent 284,674. In such compressors, the gas input opening is coupled to the atmosphere during starting of the compressor when the suction line thereof is closed. At this point, a very high vacuum is present on the suction side of the compressor and the compression gas is compressed to atmospheric pressure when it reaches the output opening of the compressor. Noise generating turbulence accordingly cannot occur in the liquid ring of the compressor. During normal operation, however, a lower vacuum exists on the suction side of the compressor and the gas pressure exceeds atmospheric pressure within the impeller cell disposed ahead of the gas input opening. A check valve is provided in the compressor behind the opening to prevent gas from escaping from the impeller cell through this opening, thus reducing the output of the compressor, i.e., gas ballast is fed into the compressor impeller only under certain operating conditions.
Low vacuum and high vapor pressure in the liquid ring of the compressor cause vapor bubbles to form within the liquid ring. These vapor bubbles implode at higher pressures, i.e., in the vicinity of the output openings of the compressor, and cause heavy erosion at the adjacent compressor parts. To prevent such cavitation phenomena, limitations must be imposed on the vacuum of the compressor which severely limit the operating range of the compressor. Alternatively, the liquid ring could be formed by a lower vapor pressure liquid, but such a solution is practical, because of process and cost considerations, only in isolated instances.